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There are MPPTs, microprocessors, labeled "smart controllers". I'm poor, I got a Chinese PWM controller (Raggie, RG-505,30amps), with feauters that would impress any solar newbie (3stage charging, discharge capacity control (IDK what that is), accurate temp. compensation, reverse protection, battery LVP OVD OCP HVDP).Wow! But at the end not a smart charger! Should I worry my sealed lead acid (gel) battery get gassed or blow up one day since I got a "non-smart" controller? Does my controller really do what it says?
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Hi Feisal,
If you really have gel batteries, make sure that they are not charging at a higher voltage than 14.4 volts or battery manufacturers specs. Too high a voltage can cause gas bubbles to form in the gel and shorten the life of the batteries.
Usually gel batteries are used in UPS and telecom applications. Although they can be used in solar applications, AGM and FLA lead acid batteries are much more widely used. Hopefully your charge controller has a charging profile for gel batteries.
I looked for the manual online but the company website has no specs or manual available.
Good luck3.6 kw PV, Classic 150, Radian GS4048A, LFP 195A -
The issue for Gel batteries is they cannot be charged fast, greater than C/20. If charged faster than C/20 will cause gassing which causes cracks and voids in the Gel Electrolyte and the damage is permanent and accumulative. It dries the Gel out. Think of that Jello mold from Christmas you just found in the back of your refrigerator. In addition they use lower voltages which not many chargers are built for. Gel Batteries are used for Emergency Lighting, Alarm Systems, and some Communications System where they use a FLOAT Mode chargers. You should never use 3-Stage Chargers on them as they cannot tolerate the higher voltages fast chargers use.
Both AGM and Gel have a few huge disadvantages. They cost roughly twice as much as Flooded. Last roughly half as long as Flooded, You cannot determine SOC or Health.
For the above reasons Gel's should never be used in any daily cycle applications especially solar.. Any properly designed solar system will have to use high charge rates greater then C/20 with C/10 being typical. Additionally they do not tolerate 3-Stage charging algorithms every manufactured charge controller uses.
AGM's have some applications. AGM's can tolerate very high charge rates and can also deliver high discharge rates. This can useful in locations with low Solar Insolation where you have to use very high charge rates of C/4 to C/2. On the discharge side Many AGM's can deliver very high discharge rates without excessive voltage sag. AGM's are also preferred in mobile applications where spills cannot be tolerated like in a Airplane. AGM's were developed for the Aerospace industry. Another application is for extreme cold environments and by extreme I mean -40 C or F. If you live in a place that cold, you should not be using Solar with the exception of aircraft or satellites orbiting earth. So AGM's have an application but be sure you understand at the end of the day they will cost you roughly 4 times more than Flooded and sensitive to over charging and can be damaged easily as you cannot determine SOC or Health.MSEE, PEComment
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I can't find any good information online for an RG-505. Possibly Raggie does not make that model anymore?
Depending on just how low the price was, it may not actually be an MPPT CC. Have you ever measured to confirm that the output current (at around 12V) is really higher than the input current (at around 24V) when the CC is in Bulk charging mode?
Some really cheap off-brand Chinese "MPPT" controllers are really just PWM with some added circuitry to make you think that it is doing MPPT.SunnyBoy 3000 US, 18 BP Solar 175B panels.Comment
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